Precipitation sensor

ABSTRACT

A precipitation sensor having two buckets secured to each other for tilting movement between two end positions, is provided with a precipitation collecting and distributing means which collects precipitation during tilting of the buckets and has a normally closed valve operated by the buckets to open when the same are in the end positions so that the collected precipitation is alternately discharged into the buckets. Evaporation retarding covers with small inlet cutouts close the tops of the buckets, adjustable elastic abutments stop the buckets without bouncing back, and magnetic switch means generate a counting pulse for each tilting movement.

United States Patent Kahl et a1. 1 1 Dec. 12, 1972 [54] PRECIPITATIONSENSOR FOREIGN PATENTS OR APPLICATIONS 1 Inventors; Gmld Kill/l, LaMesa, Califi; 505,379 5/1939 Great Britain ..177/94 f i Guldelli Guidi,Bologna, 180,834 8/1966 U.S.S.R. ..73/171 ta y [7 3] Assignees: KahlScientific Instrument Corpora- Primary Examiner-Richard Queisscr tion,Cajon, Calif.; Societa ltaliana Assistant Examiner-Marvin SmollarApparecchi Precisione S.p.A., Bolog- Attorney-Michael S. Striker na,Italy; part interest to each [221 Filed: June 23, 1970 [571 ABSTRACT[211 App]. 49,033 A precipitation sensor having two buckets secured toeach other for tilting movement between two end positions, isprovided'with a precipitation collecting [:2] $5.81 "vs/13 mm: anddistributing means which collects precipitation 23 g during tilting ofthe buckets and has a normally closed valve operated by the buckets toopen when the same are in the end positions so that the collectedprecipita- [56] References Cited tion is altematelv discharged into thebuckets. Evaporanon retardmg covers w1th small mlet cutouts UNITEDSTATES PATENTS close the tops of the buckets, adjustable elastic abut-606,601 6/1898 Thayeretal ..177/94 x mm P the buckets Withm" bwncingback, and 2,202,452 5/1940 Hildabrand ..73/171 magnetic switch meansgenerate a counting pulse for 3,243,999 5/1966 Barker .L, ..73/171 eachtilting movement. 3,465,327 9/1969 Schroter ..335/205 X 3,322,917 5/1967Furlow ..335/205 X 12 Claims, 5 Drawing Figures 3 I9 I 7- H 18 f M 17 oH Q g '4 PATENTED DEC 12 I972 mAHLSICO [NW mole! I GERALPJ 1PRECIPITATION SENSOR BACKGROUND OF THE INVENTION SUMMARY OF THEINVENTION It is an object of the invention to overcome the disadvantagesof tilting bucket sensors according to the prior art, and to provide aprecipitation sensor which accurately measures the amount ofprecipitation.

Another object of the invention is to provide a precipitation sensor ofthe tilting bucket type in which precipitation is accumulatedalternately in two buckets, collected during the tilting movement of thebuckets, and discharged into one or the other bucket when the same arein an end position.

Another object of the invention is to prevent evaporation of accumulatedprecipitation from the buckets.

Another object is to count the tilting movements of the buckets bymagnetic switch means without substantially increasing the mass of thetilting parts of the apparatus.

Another object of the invention is to prevent bouncing of the bucketswhen stopped in end positions.

With these objects in view, a precipitation sensor according to theinvention comprises supporting means, preferably including a housing;precipitation collecting and distributing means mounted on thesupporting means having an inlet and an outlet for precipitation,

and including valve means, preferably a check valve, in

the outlet; first and second buckets secured to each other mounted onthe supporting means for tilting movement together between a firstposition in which the inlet portion of the first bucket is located underthe outlet, and a second position in which the inlet portion of thesecond bucket is located under the outlet; valve actuating means,preferably including two actuators respectively secured to the first andsecond buckets for opening the valve means in the first and secondpositions of the buckets, and for effecting closing of the valve meansduring the tilting movement of the buckets; and counting means,preferably a magnetic pulse generator, operated by the buckets duringeach tilting movement.

In the first position, precipitation is accumulated in the first bucket,while the second bucket discharges accumulated precipitation through aspout. In the second position, precipitation is accumulated in thesecond bucket, while the first bucket discharges accumulatedprecipitation.

Precipitation flows through the outlet of the collecting anddistributing means into one or the other bucket, depending on in whichend position the buckets are located. In an intermediate position of thebuckets assumed during tilting of the same, the actuating means do notengage the valve member so that the valve closes and any precipitationoccurring during this time, is collected until the valve opens again andthe collected precipitation can flow into one of the buckets.

The buckets are preferably closed by evaporation retarding covers whichhave small cutouts respectively located under the valve controlledoutlet in the two end positions of the buckets. The two actuators aresecured to the buckets, respectively, and project out of the inletcutouts of the covers into the region of the valve means. i

In the preferred embodiment of the invention, the tilting buckets areconnected by a shaft with a shielding plate provided with a cutout whichpermits the flux of a permanent magnet to actuate a magnetic switch whenthe buckets assume an intermediate position during the tilting movement.

The-novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWIN FIG. 1 is a perspective front view,partly broken off, and illustrating an embodiment of the invention;

FIG. 2 is a fragmentary perspective front view illustrating a magneticswitch device used in the embodiment of FIG. 1;

FIG. 3 is a fragmentary front view illustrating the magnetic switchdevice in an operative condition;

FIG. 4 is a fragmentary side elevation of the switch device; and

FIG. 5 is a fragmentary front elevation illustrating a detail of theembodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, asupporting base 22 is provided with a level vial 16 by which thehorizontal position of its top plate can be ascertained. A circularrecess 21 receives the lower end of a pot-shaped cover 3 which enclosesa supporting housing 20 having a detachable top portion. An inlet funnell is mounted by means of a fitting 2 on the top plate of the protectivedust cover 3, and terminates in a valve assembly mounted on the topplate 19 of housing 20. As best seen in FIG. 5, the valve assemblyincludes a valve housing 4 with a circular seat on which a light ball 5rests due to the action of the force of gravity, or due to the provisionof a small spring, not shown. When the check valve 4, 5 is in the normalclosed position, precipitation falling into funnel l is collected in thesame, but when check valve 4, 5 is opened by lifting ball 5, thecollected precipitation flows out of the outlet of the check valve intoinlet cutouts 1.8 in top covers 7 of tilting buckets 8. Consequently,the assembly I, 2, 4, 5. constitutes a means for collecting anddistributing precipitation.

The buckets 8 are separated by a common wall 8a and have substantiallyslot-shaped spouts 17 at the outer ends of the buckets. A shaft 9projects from the buckets in the plane of the common wall 8a; and ismounted for angular movement with the buckets 8 in bearings of the wallsof housing 20.

An actuator 6 is secured in the interior of each bucket 8 and has acurved portion projecting out of the inlet cutouts 18 of the coverplates 7 of buckets 8, so

that, when the buckets tilt about the axis of shaft 9, the curved freeends of actuators 6 move along a circular path into the region of ballof the check valve.

In the end position shown in FIG. 1, the left bucket 8 receivesprecipitation from the outlet of check valve means 4, 5 whose valvemember 5 is lifted from its seat by the respective actuator 6. Since theradius of curvature of the curved free end of each actuator 6 is smallerthan the radius of curvature of the path along which the actuators 6move during tilting of the buckets, the frictional contact between theactuators 6 and ball 5 is minimal, and the ball 5 is not substantiallyworn off even after prolonged use. Since ball 5 retains its shape,leakage from the valve 4, 5 due to wear is prevented.

When a certain amount of precipitation has accumulated in the leftbucket 8, the center of gravity of the tiltable buckets is displaced sothat the buckets 8 tilt together in counterclockwise direction out ofthe position illustrated in FIG. 1 to another end position in which theinlet cutout 18 of the other bucket 8 is located under the outlet of thevalve means 4, 5. In this second end position of the buckets, theactuator 6 of the bucketvon the right engages the ball 5 of check valve4, 5, and opens the same so that precipitation flows through the outletof the valve means into the bucket on the right as viewed in thedrawing. During the tilting movement from one to the other endpositions, the buckets 8 assume a position in which none of theactuators 6 engages ball 5 so that the check valve 4, 5 closes andpermits no precipitation to flow into the buckets, or onto the commonseparating wall 8a.

As compared with the prior art in which the funnel 1 is connected by anopen tube with the buckets, the prior art construction causes errorsinthe measurement when the bucket is in motion due to the fact that it isalready filled to the proper amount. Excessive precipitation enteringthe filled bucket is then not measured, and some precipitation is lostin the prior art constructions by striking the common separating wall8a.

} Due to the above-described operation of the precipitation collectingand distributing means 1, 2, 4, 5 by the actuator means 6, precipitationis collected during the tilting movement of the buckets, and dischargedinto one or the other bucket when the same are in end positions.

The buckets 8 are made of lightweight metal rather than of a plasticmaterial in order to assure geometric constancy of shape andcalibration.

The top covers 7 retard evaporation of precipitation accumulated in thebuckets, and the inlet cutouts 18 in the same are as small as possible,and have such a size that the outlet of the valve 4, 5 is located aboutone or the other inlet cutout 18 in the two tilted end positions of thebuckets 8. It is evident that open buckets according to the prior artwill have a higher evaporation than the closed buckets of the invention,which will influence the measured amount of precipitation, andconsequently the accuracy of the measurement. Since the function of thesensor is to actuate other mechanism at the occurrence of a specificvolume of accumulated precipitation, any liquid lost due to evaporationwould cause an error in measurement.

When sufficient precipitation is accumulated in one of the buckets todisplace the center of gravity sufficiently in relation to the axis ofshaft 9, buckets 8 tilt, and the actuator 6 momentarily releases theball 5 of check valve 4, 5 so that the same closes. The filled bucket isturned to an inclined position in which it discharges the accumulatedprecipitation through the spout l7.

Shaft 9, which turns with buckets 8 carries at the free end thereof, twodiametrically disposed stop arms 10 which respectively cooperate withelastic abutments 14 whose positions can be adjusted by threaded nuts14a.

At the end of each tilting movement, one of the stop arms 10 abuts theelastic abutment l4 and stops the buckets 6 in one end position.Depending on the adjustment of the abutments 14, the angle of tiltingwill be greater or smaller, which correspondingly influences the amountof precipitation which can be accumulated in each bucket 8 before thebuckets turn to the other end position.

The elastic abutments 14 have the advantage that the stop arms 10, andthe buckets 8 connected with the same by shaft 9, will not bounce backafter each tilting movement of the buckets 8.

A permanent magnet 13 is secured to a wall of housing 20 in a verticalposition, and is preferably located in the vertical plane passingthrough the axis of shaft 9, in which also the outlet of theprecipitation collecting and distributing means 1, 2, 4, 5 is located.

Registering with permanent magnet 13 in the same vertical plane, is apair of parallel magnetic dry reed switches 12, best seen in FIGS. 2 and3, which are connected in parallel. A non-magnetizable shielding plate11 is secured to shaft 9 and stop arms 10, and is formed with a cutout11a which registers with the permanent magnet 13 and the magnetic switchmeans 12 in the position of FIG. 3 when the buckets 8 momentarily assumea central position in which the common partitioning wall 8a is locatedin a vertical plane. In the two tilted end positions, the shieldingplate 11 and its cutout 11a are in the position shown in FIG. 2, and ina symmetrical position, not shown, in which portions of thenon-magnetizable shielding plate 11 are located between the permanentmagnet 13 and the magnetic switch means 12. In these positions, the fluxof magnet 13 cannot penetrate to the magnetic switches 12, and the sameremain open. In the central position shown in FIG. 3, the magnetic fluxof permanent magnet 13 passes through the cutout 11a to the magneticswitch means 12 and closes the same so that a counting impulse isgenerated which is counted by suitable means which register the numberof tilting movements of the buckets so that the total accumulated anddischarged precipitation can be calculated.

While a single magnetic switch 12 would be suffi cient, it is preferredto provide two magnetic switches 12 connected in parallel into thecircuit, not shown, so that the generation of counting pulses iscontinued even if one of the switches fails.

Hermetically closed magnetic switches are used which assure a long-termoperation by a mechanism having a small mass which improves thereliability of the apparatus and furnishes reproduceable and accuratemeasurements. Unlike mercury switch systems, the mass to be shifted witheach tilting movement is very small, which improves the sensitivity ofthe sensor. Unlike in mechanical switches, there is no minimum force orchange in inertia associated with the dry reed switches used inaccordance with the invention.

By using a lightweight non-magnetizable shielding plate 11, instead ofmounting the heavy permanent magnet directly on the shaft of thebuckets, the weight and inertia of the heavy magnet has no influence onthe tilting movement, and the mass of the lightweight shielding plate 11is negligible. Due to the fact that the switch 12 is mounted in avertical position, the actuation of the switch is effected during themiddle of the tilting motion when the buckets pass through anintermediate vertical position. In prior art arrangements, horizontallymounted switches are used which are actuated at the end of each tiltingcircle, which causes errors due to the bouncing back of the bucketassembly and of the switch actuator, causing multiple switch closures.Since in accordance with the invention, only one switch actuation takesplace during each tilting movement, no errors due to bouncing back cantake place, and furthermore, bouncing back of the tilting bucketassembly is reduced or prevented by provision of the elastic abutments14.

Electrical connections are made at a terminal board 15 so thatelectrical counters or recording means may be used to monitor the numberof tilting motions of bucket assembly 8 and thus determine the totalamount of precipitation in a given period of time. By choosing theproper funnel 1 of the precipitation collecting and distributing means,measurements can be obtained in increments of 0.01 inch ofprecipitation.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofprecipitation sensors differing from the types described above.

While the invention has been illustrated and described as embodied in aprecipitation sensor having means for collecting precipitation duringtilting of buckets, it is not intended to be limitedto the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. Precipitation sensor comprising, in combination, supporting means;precipitation collecting and distribution means having an inlet and anoutlet for precipitation; bucket means including first and secondbuckets secured to each other and mounted on said supporting means fortilting movement together between a first position in which an inletportion of said first bucket is located under said outlet foraccumulating of said precipitation while said second bucket dischargesaccumulated precipitation, and a second position in which an inletportion of said second bucket is located under said outlet foraccumulating precipitation while said first bucket dischargesaccumulated precipitation; and countingmeans operated by said bucketmeans during each tilting movement, said counting means including magnetmeans carried by said supporting means, magnetic switch means mounted onsaid supporting means aligned with said magnet means in a verticalplane, and a non-magnetizable shielding plate secured to said bucketmeans for angular movement therewith and having a cutout registeringwith said magnetic switch means and said magnet means in said verticalplane during tilting movement of said bucket means to generate acounting pulse by permitting magnetic flux to flow from said magnetmeans to said magnetic switch means.

2. Precipitation sensor as defined in claim 1, and including valve meansin said outlet so that precipitation is collected while said valve meansis closed and discharged while said valve means is open, and valveactuating means secured to said bucket means for opening said valvemeans in said first and second positions of said bucket means and foreffecting closing of said valve means during tilting movement of saidbucket means between said first and second positions.

3. Precipitation sensor as claimed in claim 2 wherein said valve meansincludes a valve member biassed to move to a closed-position; andwherein said actuator means engage and open said valve member in saidfirst and second positions of said bucket means, and release said valvemember for movement to said closed positionat the beginning of saidtilting movement so that said valve member closes said valve means whenneither of said inlet portions is located under said outlet.

4. Precipitation sensor as claimed in claim 3 wherein said valve meansis a check valve; wherein said valve member is a ball biassed at leastby gravity to move to said closed position; and wherein said actuatormeans is located under said valve member and lifts the same to open saidvalve means when saidbucket means is in said first and second positions.

5. Precipitation sensor as claimed in claim 2 wherein said valve meansis a normally closed check valve; wherein said actuator means includes afirst actuator secured to said first bucket and a second actuatorsecured to said second bucket spaced from said first actuator; whereinsaid first actuator engages and opens said valve means in said firstposition and said second actuator engages and opens said valve means insaid second position; and wherein said valve means is located betweensaid first and second actuators during tilting movement of said bucketmeans between said first and second positions, and is closed.

6. Precipitation sensor as claimed in claim 5 wherein said valve meanshas a movable valve member; wherein each of said actuators has anengaging portion moving along a curved path during tilting movement ofsaid bucket means; and wherein each engaging portion is curved at asmaller radius of curvature than the respective path so that only asmall surface portion of said valve member is engaged by each engagingportion.

turnably mounted on said housing; wherein at least one end of said shaftprojects out of said housing; and wherein said shielding plate issecured to said shaft end.

9. Precipitation sensor as claimed in claim 8 wherein said magneticswitch means are located in said vertical plane, said permanent magnetmeans being fixedly supported by said housing in said vertical plane.

10. Precipitation sensor as claimed in claim 1 wherein saidmagneticswitch means include two adjacent parallel reed switches simultaneouslyoperated by said permanent magnet means and connected in parallelwhereby a counting pulse is generated even if one of said switchesfails.

11. Precipitation sensor comprising a housing; precipitation collectingand distributing means mounted on said housing and having an inlet andan outlet for precipitation and including a normally closed check valvein said outlet so that precipitation is collected while said valve isclosed and discharged when the same is opened; bucket means includingfirst and second buckets secured to each other and a horizontal shaftmounting said buckets on said housing for, angular tilting movementabout the shaft axis between a first position in which an inlet portionof said first bucket is located under said outlet for accumulatingprecipitation while said second bucket discharges accumulatedprecipitation and a second position in which an inlet portion of saidsecond bucket is located under said outlet for accumulatingprecipitation while said first bucket discharges accumulatedprecipitation, said collecting and distributing means being locatedsubstantially in a vertical plane passing through said shaft axis; valveactuating means comprising a first actuator secured to said first bucketand engaging and opening said valve in said first position of saidbucket means, and a second actuator secured to said second bucket andengaging and opening said valve in said second position of said bucketmeans, said valve being located between said actuators during tilting ofsaid bucket means and closed during such tilting movement; and countingmeans operated by said bucket means during each tilting movement andcomprising magnetic switch means located in said vertical plane,permanent magnet means fixedly supported by said housing in saidvertical plane, and a non-magnetizable shielding plate secured to saidshaft for angular movement therewith and having a cutout registeringwith said magnetic switch means and said permanent magnet means in saidvertical plane during tilting movement of said bucket means, wherebyflux flowing from said permanent magnet means through said cutout insaid plate energizes said magnetic switch means to generate an electricI countin pulse. D

l2. recipitation sensor as defined in claim 11,

1. Precipitation sensor comprising, in combination, supporting means;precipitation collecting and distribution means having an inlet and anoutlet for precipitation; bucket means including first and secondbuckets secured to each other and mounted on said supporting means fortilting movement together between a first position in which an inletportion of said first bucket is located under said outlet foraccumulating of said precipitation while said second bucket dischargesaccumulated precipitation, and a second position in which an inletportion of said second bucket is located under said outlet foraccumulating precipitation while said first bucket dischargesaccumulated precipitation; and counting means operated by said bucketmeans during each tilting movement, said counting means including magnetmeans carried by said supporting means, magnetic switch means mounted onsaid supporting means aligned with said magnet means in a verticalplane, and a non-magnetizable shielding plate secured to said bucketmeans for angular movement therewith and having a cutout registeringwith said magnetic switch means and said magnet means in said verticalplane during tilting movement of said bucket means to generate acounting pulse by permitting magnetic flux to flow from said magnetmeans to said magnetic switch means.
 2. Precipitation sensor as definedin claim 1, and including valve means in said outlet so thatprecipitation is collected while said valve means is closed anddischarged while said valve means is open, and valve actuating meanssecured to said bucket means for opening said valve means in said firstand second positions of said bucket means and for effecting closing ofsaid valve means during tilting movement of said bucket means betweensaid first and second positions.
 3. Precipitation sensor as claimed inclaim 2 wherein said valve means includes a valve member biassed to moveto a closed position; and wherein said actuator means engage and opensaid valve member in said first and second positions of said bucketmeans, and release said valve member for movement to said closedposition at the beginning of said tilting movement so that said valvemember closes said valve means when neither of said inlet portions islocated under said outlet.
 4. Precipitation sensor as claimed in claim 3wherein said valve means is a check valve; wherein said valve member isa ball biassed at least by gravity to move to said closed position; andwherein said actuator means is located under said valve member and liftsthe same to open said valve means when said bucket means is in saidfirst and second positions.
 5. Precipitation sensor as claimed in claim2 wherein said valve means is a normally closed check valve; whereinsaid actuator means includes a first actuator secured to said firstbucket and a second actuator secured to said second bucket spaced fromsaid first actuator; wherein said first actuator engages and opens saidvalve means in said first position and said second actuator engages andopens said valve means in said second position; and wherein said valvemeans is located between said first and second actuators during tiltingmovement of said bucket means between said first and second positions,and is closed.
 6. Precipitation sensor as claimed in claim 5 whereinsaid valve means has a movable valve member; wherein each of saidactuators has an engaging portion moving along a curved path duringtilting movement of said bucket means; and wherein each engaging portionis curved at a smaller radius of curvature than the respective path sothat only a small surface portion of said valve member is engaged byeach engaging portion.
 7. Precipitation sensor as claimed in claim 1wherein said supporting means include a supporting housing in which saidbucket means is located; wherein said bucket means includes a horizontalshaft mounting said first and second buckets on said supporting housingfor angular tilting movement about an axis between said first and secondpositions; and wherein said collecting and distributing means is mountedon said housing in a vertical plane passing through said axis of saidshaft.
 8. Precipitation sensor as claimed in claim 7 wherein said shaftis fixedly secured to said bucket means and turnably mounted on saidhousing; wherein at least one end of said shaft projects out of saidhousing; and wherein said shielding plate is secured to said shaft end.9. Precipitation sensor as claimed in claim 8 wherein said magneticswitch means are located in said vertical plane, said permanent magnetmeans being fixedly supported by said housing in said vertical plane.10. Precipitation sensor as claimed in claim 1 wherein said magneticswitch means include two adjacent parallel reed switches simultaneouslyoperated by said permanent magnet means and connected in parallelwhereby a counting pulse is generated even if one of said switchesfails.
 11. Precipitation sensor comprising a housing; precipitationcollecting and distributing means mounted on said housing and having aninlet and an outlet for precipitation and including a normally closedcheck valve in said outlet so that precipitation is collected while saidvalve is closed and discharged when the same is opened; bucket meansincluding first and second buckets secured to each other and ahorizontal shaft mounting said buckets on said housing for angulartilting movement about the shaft axis between a first position in whichan inlet portion of said first bucket is located under said outlet foraccumulating precipitation while said second bucket dischargesaccumulated precipitation and a second position in which an inletportion of said second bucket is located under said outlet foraccumulating precipitation while said first bucket dischargesaccumulated precipitation, said collecting and distributing means beinglocated substantially in a vertical plane passing through said shaftaxis; valve actuating means comprising a first actuator secured to saidfirst bucket and engaging and opening said valve in said first positionof said bucket means, and a second actuator secured to said secondbucket and engaging and opening said valve in said second position ofsaid bucket means, said valve being located between said actuatorsduring tilting of said bucket means and closed during such tiltingmovement; and counting means operated by said bucket means dUring eachtilting movement and comprising magnetic switch means located in saidvertical plane, permanent magnet means fixedly supported by said housingin said vertical plane, and a non-magnetizable shielding plate securedto said shaft for angular movement therewith and having a cutoutregistering with said magnetic switch means and said permanent magnetmeans in said vertical plane during tilting movement of said bucketmeans, whereby flux flowing from said permanent magnet means throughsaid cutout in said plate energizes said magnetic switch means togenerate an electric counting pulse.
 12. Precipitation sensor as definedin claim 11, wherein said bucket means include first and secondevaporation retardation covers on top of the first and second buckets,respectively, said first and second covers having first and second inletcutouts respectively forming said inlet portions and being respectivelylocated under said outlet means when said bucket means are in said firstand second positions.